<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>06_外间距测试</title>
</head>
<style>
    body{
        margin:0;
        /*去掉body自带的四个方向的外间距*/
    }
    *{  /*去掉所有元素默认自带的内外间距*/
        margin:0; /*外间距*/
        padding:0; /*内间距*/
    }
</style>
<body>
    <!--.fu>.z-->
    <div class="fu">

        <div class="z1">子元素1</div>
        <div class="z2">子元素2</div>
        <div class="z3">子元素3</div>
        <div class="z4">子元素4</div>

    </div>

</body>
</html>